| Objective To Investigate the peaks alteration regularity of H Magnetic Resonance Spectroscopy ('HMRS) and the relation between 'HMRS and the expression of Heat Shock Protein 70(HSP70) in the brain of neonatal piglet with hypoxia ischemic encephalopathy (HIE), and provide an important reliable criterion for the early diagnosis, clinical treatment and prognosis evaluation of HIE.Methods 7-days-old healthy neonatal piglets were divided into 3 groups randomly: control group (n=5), sham operation group (n=5) and HI groups (Oh group,3h group,6h group, 12h group, 18h group and 24h group after HI, n=5). All piglets were examed respectively by MRI and 'HMRS with 1.5T GE Electric scanner. SE sequences and point resolved spectroscopy sequence (PRESS) were used for routine examination.TR 1500ms, TE 135ms ,VOI 20mm X 20mm X 20mm, were used for 'HMRS. The metabolites that detected by spectroscopy included N-acetylaspartate (NAA), choline compounds (Cho), creatine compounds (Cr), myo-inositol (ml), lactate(Lac), glutamate and glutamine compounds (Glx). The expression of HSP70 was analyzed in the HI cerebra of the neonatal piglets, and the ratios of NAA to Cr,Cho,Cr+Cho, and the ratios of Lac,Glx,mI to Cr, Cho,Cr+Cho,NAA were calculated separately. Using HE dyeing and immunohisto-chemistry methods, the pathology changes and the expression of HSP70 in the brain were observed at the all groups.Results (1) 'HMRS manifestations of control group and sham operation group (n:=5):The peaks of Cho ,NAA and Cr were elevated, and those of ml were decreased slightly, while peaks of Glx and Lac were flattened or undetectable. The amplitudes in a high-to-low order were as follows: Cho,NAA,Cr,mI,Glx and Lac. Thesham operation group ratios of NAA/Cr 1.41+0.01, NAA/Cho 0.95 + 0.02, NAA/Cr+Cho 0.54?.02, Lac/Cr 0.11+0.042, Lac/Cho 0.10?.01, Lac/Cr+Cho 0.06 + 0.01, Lac/NAA 0.11+0.01; The ratios of metabolites sham operation group showed no significant difference (p>0.05) ,compared with those of the control group. (2) 'HMRS manifestations of HI group (n=30): NAA/Cr=1.24 + 0.04, NAA/Cho=0.74 ?.03, NAA/Cr+Cho=0.47?.03.While the results of NAA/Cr (1.40 + 0.02),and NAA/Cr+Cho (0.53 +0.04) showed no significant difference (p>0.05),compared with the control group after HI 3h, however the ratio of NAA/Cho 0.78 ?.04 (p<0.05). The ratios of NAA/Cr, NAA/Cho, NAA/Cr+Cho decreased gradually after HI 6h~24h. The peaks of Lac, presenting typical double-peak appearances, were elevated after HI Oh, Lac/Cr=1.88 ?0.02, Lac/Cho=l .07 ?0.02, Lac/Cr+Cho=0.68 ?0.02. After HI 3h~24h the peaks of Lac declined significantly gradually(p<0.01); The peaks of Glx, which were also elevated slightly and exhibited zigzag appearance, showed no significant difference (p>0.05); While that of ml has no significant decreased (p>0.05).(3)Pathology results showed normal at the control group and sham operation group ; However the cerebral cellular swelling, hemangiectasia and hyperemia after HI Oh.Slight edema area relieved gradually with the time went on after HI 3~24h, however, the severity edema area aggravated gradually, cellular necrosis increased and multiple focal necrosis area presented after HI 24h. (4) The expression of HSP70 was not observed at the control group and sham operation group. But the expression of HSP70 was observed in a small number in the cerebra until 3h after HI. It increased during 6h~24h in the slight edema area and reached its peak at 24h (12.43 + 2.51), while in the severity edema area it did not rise obviously. (5) There was probable negative correlation between the ratios changes of NAA, Lac separately to Cr, Cho, Cr+Cho and the expression of HSP70 in the HIE slight edema area, however no significant correlation in the severity edema area. There \vas probable no correlation between the ratios of Glx ,ml respectively to Cr,Cho,Cr+Cho and the expression of HSP70 in the brain.Conclusions (1) NAA and Lac are the most sensitive markers of early brain damage, and NAA/ Cho, Lac/ NAA,Lac /Cr,Lac /Cho,Lac /Cr+Cho are the best indexes whichcan q... |
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